Generally, in an integral type suspension provided with an integral link for controlling a swing trajectory (a so-called recession angle) of a rear wheel in a side view when the rear wheel moves up and down, all the load in a vehicle front-rear direction is exerted on a rear subframe because a trailing link is not provided. In view of the above, generally, an H-shaped lower arm is provided as a lower arm in order to secure rigidity of the rear subframe.
On the other hand, in order to secure comfort of a passenger on a rear seat and to secure a low hip point, there is a demand for lowering the height of a rear seat pan. As a result, an installation space of a rear subframe tends to be narrowed from constraints on the layout with respect to a rear seat pan, or the like. It is difficult to support the lower arm, and to linearly extend a front cross member or a side cross member of a closed sectional structure with respect to a vehicle body support portion of a rear subframe.
Specifically, in a configuration, in which a rear subframe is disposed in a narrow space of a lower portion of a rear seat pan where it is impossible to connect a front cross member and a side member, while securing a sufficient closed sectional structure, it is difficult, in terms of space, to extend a front cross member and a side member in a straight manner, and to provide a lower-arm front-side support portion and a toe control link support portion at positions close to each other, while causing closed sections of the front member and the side member to pass straightforwardly in a vehicle width direction and in a vehicle front-rear direction. In addition to the above, in a case where a lower arm is an H-shaped lower arm as described above, there is also a problem that the space efficiency is lowered.
Patent Literature 1 discloses an integral-type rear suspension. In a conventional structure disclosed in Patent Literature 1, a front-side arm support portion of an H-shaped lower arm projects downwardly from a front portion of a side member. Further, a toe control link support portion is formed at a position further rearwardly away from a rear-side arm support portion of the lower arm. Therefore, it is difficult to dispose a lower-arm support portion and a toe control link support portion in a dense and compact manner.
Further, Patent Literature 2 discloses a configuration, in which a box-shaped arm support portion is formed on a side member extending in a vehicle front-rear direction. This configuration is such that the arm support portion projects downwardly from a side member. Therefore, there is room for improvement in the aspect of miniaturization and enhancing rigidity.